Many of the products we buy today are made from or contain plastic. Imagine how headphones or computers might look without plastics.This activity will allow your club to explore how to make plastics and experiment with different ideas for applications.

in partnership with

Plastic......is traditionally made from crude oil, which is a non-renewable fossil fuel.

Oil is also a ready made fuel which is cheap to convert into energy, but when burnt gives off atmospheric pollutants, including greenhouse gases, and we only have a limited supply.

Although we are increasing how much plastic we recycle, we need to look for alternative raw materials for making new plastics so that we do not waste the oil we have left and to reduce the amount of greenhouse gases we release into the atmosphere.

What you need Pint of whole milk

20 ml white vinegar

Water

Protective gloves

Muslin (or a cotton tea towel)

These figures can be scaled down so more groups can do the experiment using a ratio of 150 ml of milk to 5 ml of vinegar.

This process can be done on a hob with a saucepan, spoon and sieve, or in the lab using a Bunsen burner (plus tripod, gauze and heatproof mat) beaker, stirring rod and sieve. You can use filter paper but this is very slow. Try coffee filters or tea strainers.

Note for STEM Ambassadors: schools will have many of the items you need, so check with the teacher before your session. A risk assessment should be done before starting this activity.

Milking it This session needs two club

slots which are a week or more apart. Following the extras will create a longer project.

2 Milking it

What to do This method will enable you to make a small amount of plastic. Think about what you are going to use it for. Design a basic idea for a plastic, engineered product that has a short life span. For example, your group could design a seasonal decoration.

Warm the milk in the container (saucepan or beaker) and stir in the measured volume of vinegar but DO NOT BOIL (just heat until you see vapours).

When lumps begin to form, turn the heat off. Continue stirring for a minute and then leave.

Once the mixture is cooled, sieve it leaving the lumps behind.

Wearing protective gloves, wash the milk lumps, mould them into shapes and leave on the muslin (or tea towel) to dry.

Some extras... You can extend this session by using different types of milk, such as goats milk, and different acids, such as lemon juice.

This session can also lead to a discussion on recycling and sustainable materials.

Does your school recycle?

What types of materials can be recycled and how does this work?

Why not try making other plastics e.g. make a plastic from potato starch.

A good example of this idea has been produced by the Royal Society of Chemistry and can be found at: www.tinyurl.com/rscplastic

Curriculum links Using this activity you can discuss:

England Science: Chemical reactions. Materials.

Scotland Science: Chemical Changes 3-19a Technological developments in society (2-01a&b, 2-02a, 3-01a, 3-02a).

Explanation Plastics are made from long chain molecules (polymers), which can be heated and moulded.

In this case, the long chain molecule is the milk protein (caesin) which precipitates out of the milk when it reacts with the vinegar (a weak acid).

Inspired by Mick O’Hare, How to Fossilise Your Hamster, Profile Books, 2007.

Industry sector

Research

What I do on an average day

I spend most of the day playing with materials in my lab – trying to create new materials or make existing materials in a more environmentally friendly way. Currently I am looking at ways to make catalysts and materials to take carbon dioxide out of the atmosphere.

My favourite part of my job 

I really enjoy going to conferences, finding out about all the amazing things people are doing and meeting the other experts.

Hobbies

I enjoy hula hooping, baking (cakes), sewing, swing dancing and cycling.

The future

I would like to continue to tackle environmental issues through materials solutions.

What is engineering?

For me engineering is about solving problems and making the world better.

Who looks at materials?Josie GoodallResearch Assistant

Handy hints Be careful; this experiment does smell!

The plastic you have made is organic and will ‘go off’ after a while. However, can your students think of suitable uses for this plastic which takes this property into account?

The product needs to be for single use or have a short lifespan. During trials students suggested:

Seasonal decorations

Fishing floats

Temporary board game pieces

This is a very quick and easy experiment.

If the milk is being slow to curdle you can try adding a little more vinegar.

While waiting for the mixture to cool, why not try a task from one of the support resources?

Milking it 3

Royal Academy of EngineeringPrince Philip House, 3 Carlton House Terrace, London SW1Y 5DG

Tel: +44 (0)20 7766 0600www.raeng.org.ukRegistered charity number 293074

This is engineeringThinking about how to manufacture and use plastics and plastic products is a good example of engineering being useful for our lives.

Materials and polymer engineers develop new products and improve upon existing ones. Have a look at related university courses at www.ucas.com. Entry requirements include A-Levels, Advanced Diplomas and Scottish Advanced Highers.

Related fields: Chemical engineering

Process Technology Apprenticeships (www.apprenticeships.org.uk) provide training for a range of skilled occupations in the chemical, pharmaceutical, petro-chemical (oil) manufacturing and refining industries. These industries produce many of life’s necessities. The chemicals and pharmaceuticals industry makes products like pharmaceuticals, soaps and toiletries, while the petroleum refining industry is responsible for turning crude oil into fuels and lubricants.

In Scotland visit www.apprenticeshipsinscotland.com and in Wales wales.gov.uk/apprenticeships

Extra mathsHow much plastic did you manage to produce (in kilograms)? How much milk do you think you would need to make enough plastic for:

A plastic lunch box?

A plastic chair?

You will have to find a ratio of milk to product for your manufacturing process and then measure or estimate the mass of a lunch box and chair.

Generously supported by

www.baesystems.com/education

Next stepsRemember there are more resources at networking.stemnet.org.uk

For more on STEM Clubs visit www.stemclubs.net

To speak with your local STEMNET representative visit www.stemnet.org.uk/regions

CREST Awards are easy-to-run, encourage students to continue with STEM subjects, and add real value to UCAS applications. To link this activity’s extra ideas to a CREST Bronze Award, contact your CREST Local Coordinator: www.britishscienceassociation.org/crestcontacts

Accredited Scheme